As a method for producing an electrode film for an electric double-layer capacitor (hereinafter referred to also as “EDLC”), there is conventionally known a production method in which activated carbon, carbon black, and a binder such as PTFE) are kneaded and then shaped into a sheet (for example, Patent Literature 1).
However, it is considered to be difficult for this method to sufficiently improve density of carbon micro-powder (activated carbon) in an electrode. Accordingly, Patent Literature 2 proposes a method for producing a polarizable electrode for a capacitor, the method comprising mixing and kneading raw materials including a carbonaceous powder, a conductive assistant, and a binder to obtain a kneaded product and then forming the kneaded product into a sheet-shaped product having a predetermined thickness by roll press, in which the kneaded product is obtained by drying and press molding a primary kneaded product prepared by mixing and kneading the raw materials, followed by pulverizing and classifying. In Patent Literature 2, it is described that this method can improve density of carbon micro-powder in the polarizable electrode and thus can contribute to increase the capacitance of a capacitor.
In addition, Patent Literature 3 discloses a method for producing a sheet-shaped polarizable electrode for an electric double-layer capacitor, the method comprising mixing and kneading raw materials including a carbonaceous powder, a conductive assistant, and a binder to obtain a kneaded product, finely graining the kneaded product to produce a shaping material, and shaping and rolling the shaping material into the electrode. It is a method for producing a polarizable electrode for an electric double-layer capacitor, which uses, as the shaping material obtained by fine graining of the kneaded product, a shaping material of lump-shaped particles having a particle diameter ranging from 47 μm or more to less than 840 μm. It is described that this method can produce a polarizable electrode having high tensile strength. Patent Literature 3 describes a method for finely graining a kneaded product in which the kneaded product is shredded by a shredding blade.